The present invention relates to centrifuge motor lubricating systems and is directed more particularly to a centrifuge motor lubricating system which circulates lubricating oil rapidly enough to provide a high degree of motor cooling, and yet which does not overlubricate the motor bearings.
Because of the critical importance of adequately lubricating the bearings of high speed centrifuge motors, considerable effort has been devoted to developing lubrication systems therefor. Among the lubrication systems which have been used prior to the present invention, one of the most effective is a system in which the shaft or spindle of the motor is provided with an internal passage having a tapered inlet that extends into an oil sump. As this shaft rotates, oil is drawn into the tapered inlet and flows upwardly along the surface of the passage and then outwardly through radial holes which are located in the vicinity of the upper and lower motor bearings. By properly selecting the size and shape of the internal passage and of the radial holes, such systems are able to provide a continuous supply of lubricating oil to the bearings. One example of a lubricating system of this type is described in U.S. Pat. No. 2,766,081 which issued in the name of E. Wiedemann on Oct. 9, 1956.
While lubricating systems of the above type are adequate in most respects, they have certain undesirable features which limit the usefulness thereof. The most important of these is the difficulty of assuring the desired distribution of oil between the upper and lower bearings. This distribution can, for example, be significantly affected by small differences in the dimensions or surface roughness of different parts of the passage, the accumulation of dirt on the surface of the passage, and other factors. As a result, one of the bearings can become overlubricated while the other is underlubricated. Both of these conditions can significantly reduce the useful life of the bearings.